Several different ways of identifying a target for a guided or homing missile are known in the art. A simple approach is to provide the missile with a location of the target, known from intelligence reports, surveillance imagery or other surveillance activity or from public sources. The missile is then guided to that location, typically in modern systems using its own onboard guidance systems, inertial and/or satellite-based. However, that approach is limited to targets that are fixed, or at least reliably known to be in a particular location at a particular time. Even in those cases, targeting can be relatively coarse, at least for small, locally mobile targets, delivering the missile only to the approximate location of the target. Moreover, if the intelligence reports or other sources prove to be inaccurate, or out-of-date, the missile is delivered to a location from which the target has left or where it has never been. Another common approach, particularly for relatively short-range missiles, is to aim the missile towards the target and to rely on radar or ladar for guidance to the target in the final phase of flight. That approach is adequate in situations in which significant returns to the radar or ladar are from the target and no other objects, or from several objects all of which are targets, but it is not good when a target is surrounded by other objects that provide strong returns.
Although guidance to a specified location remains useful in getting the missile to the vicinity of the target, more precise missile targeting to a specific target usually requires control by a human having visual contact with the target. For example, in semi-active laser targeting, a person with a direct line-of-sight to the target illuminates it with a laser of a preselected wavelength. The incoming missile includes a sensor, typically a quadrant sensor, which detects reflections of the laser wavelength from the target and the missile steers itself towards the source of those reflections. In another example, the missile includes an onboard camera or other imaging system, which relays images, from the missile in flight, to a remote human operator, whether in an aircraft or on the ground. The operator reviews the images and identifies the target. The operator then either steers the missile to the target or provides sufficient information to the missile for it to lock onto the target and steer itself towards it. In a variant of this approach, the images are provided by a camera or other imaging system on board an ISTAR-UAV circling the target or operated by a human on the ground.
However, human intervention in the targeting process—an “operator in the loop”—has many drawbacks. In the case of semi-active laser targeting, for example, the operator is required to have a line-of-sight to the target until close to the moment of detonation of the missile. Clearly, that is potentially extremely hazardous for the operator. Even where the operator is remote, communication delays and interruptions can cause problems. The operator must be trained to be sufficiently skilled in target recognition and remain vigilant in his or her monitoring of the images. There is a significant risk of error.
In recent years, there has therefore been much interest in automatic targeting of missiles to specific targets. For example, it is known to provide a missile with image processing software including a database of target shapes, so that images provided by the missile's imaging system are processed and matches to the target shape, if any, are identified. As space and power on board a missile are limited, a more common approach is to provide the image processing software to the remote human operator, so that the images are pre-processed before they are presented to the operator. Specifically, the image-processing software identifies objects in the images that are possible matches to the target shapes in the database, and highlights those objects in the images presented to the operator. That helps the operator to spot potential targets, but the final identification and designation of an object as a target is by the operator.
In another variant, images of the target are provided to the missile by an ISTAR-UAV, human on the ground, or other source, and image processing software on board the missile looks for objects in an image stream from the missile's own camera that match the image provided to the missile. This approach can require significant bandwidth between the source of images and the missile, which is often not available, and may still require an operator in the loop to make final targeting decisions, as described above.
A further difficulty is that missiles usually have only limited on-board resources, for example processors and power supplies, and so resource-intensive processes (e.g. complex image processing) are not possible.
It would be advantageous to provide improved apparatus and methods of missile targeting in which the above-described disadvantages are eliminated or at least ameliorated.